681137391 has 32 divisors (see below), whose sum is σ = 1005096960. Its totient is φ = 406879200.

The previous prime is 681137339. The next prime is 681137437. The reversal of 681137391 is 193731186.

It is not a de Polignac number, because 681137391 - 2⁹ = 681136879 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681137311) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 747226 + ... + 748136.

It is an arithmetic number, because the mean of its divisors is an integer number (31409280).

Almost surely, 2^681137391 is an apocalyptic number.

681137391 is a deficient number, since it is larger than the sum of its proper divisors (323959569).

681137391 is a wasteful number, since it uses less digits than its factorization.

681137391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1227.

The product of its digits is 27216, while the sum is 39.

The square root of 681137391 is about 26098.6089859211. The cubic root of 681137391 is about 879.8559470643.

It can be divided in two parts, 681137 and 391, that added together give a triangular number (681528 = T₁₁₆₇).

The spelling of 681137391 in words is "six hundred eighty-one million, one hundred thirty-seven thousand, three hundred ninety-one".